Cardiac rhythm management system with ultrasound for autocapture or other applications

• US 6,298,269 B1
• Filed: 04/19/1999
• Issued: 10/02/2001
• Est. Priority Date: 04/19/1999
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Sweeney, Robert J.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/294,641
• Time in Patent Office: 897 Days
• Field of Search: 607/28, 607/9, 607/32
• US Class Current: 607/28
• CPC Class Codes: A61N 1/36528 the parameter being measured by means of ultrasound

Abstract

A cardiac rhythm management system provides ultrasound autocapture capability for determining whether a stimulation has evoked a desired response from the heart, and for adjusting an energy of the stimulation based on the observed response from the heart. A first ultrasound element is disposed on a lead in the heart. A second ultrasound element is disposed elsewhere in the heart or in the implanted device. An autocapture determination circuit detennines whether motion of the heart chamber indicates a contraction in response to the stimulation, and adjusts the stimulation energy to provide only that energy which is needed to obtain capture. This saves energy, prolonging the life of the implanted device, minimizing the risk and expense to patient associated with early explantation and replacement of the implanted device. Other applications include using ultrasound for (1) determining the strength of heart contractions (2) determining dissociation between electrical and mechanical heart activity, (3) determining the volume of the heart, (4) determining the origin of sensed intrinsic electrical heart activity signals, (5) recognizing particular arrhythmias (6) disrupting cell membranes for lowering stimulation thresholds, (7) controlling the delivery of a steroid, and (8) obtaining blood flow information.

Claims

1. A cardiac rhythm management system including:

a lead, including a distal end and a proximal end, the distal end of the lead adapted for being disposed in or about a heart, the distal end of the lead including a first ultrasonic element;

a second ultrasonic element adapted for being disposed inside a living body and outside a heart chamber in which the first ultrasonic element is located; and

an electronics unit coupled to the proximal end of the lead, the electronics unit including;

an ultrasound driving circuit; and

a signal processing circuit that processes a signal that is based on ultrasound.

2. The system of claim 1, where the second ultrasonic element is adapted for being disposed in a different heart chamber than the first ultrasonic element.

3. The system of claim 1, where the second ultrasonic element is in a case carrying the electronics unit.

4. The system of claim 1, in which the signal processing circuit includes an autocapture determination module.

5. The system of claim 1, in which the signal processing circuit includes a slope detection module.

6. The system of claim 5, in which the slope detection module provides an indication of a strength of a mechanical heart contraction.

7. The system of claim 1, in which the signal processing circuit includes an amplitude detection module.

8. The system of claim 7, in which the amplitude detection module provides an indication of the volume of a mechanical heart contraction.

9. The system of claim 1, further including:

an electrode adapted for being associated with a portion of a heart; and

a sensing circuit for detecting intrinsic electrical heart activity based on at least one electrogram signal received from the electrode.

10. The system of claim 9, in which the signal processing circuit detects occurrences of heart activity based on both the ultrasound and the electrogram signal.

11. The system of claim 9, in which the signal processing circuit detects dissociation between an occurrence of heart activity based on the ultrasound and an occurrence of heart activity based on the electrogram signal.

12. The system of claim 9, in which the signal processing circuit recognizes an arrhythmia based at least in part on the ultrasound.

13. The system of claim 1, in which the signal processing circuit controls delivery of the ultrasound energy for disrupting cell membranes and lowering stimulation thresholds.

14. The system of claim 1, in which the signal processing circuit controls delivery of the ultrasound energy for controlling the release of a steroid from a steroid eluting clement.

15. The system of claim 1, in which the signal processing circuit obtains blood flow information based on the ultrasound.

16. The system of claim 1, further including a programmer remote from the electronics unit.

17. A method comprising:

disposing a first ultrasonic element in a first heart chamber;

disposing a second ultrasonic element in a living body and outside the first heart chamber;

obtaining the first electrical signal, which includes mechanical heart contration information, using at least one of the first and second ultrasonic elements; and

providing cardiac rhythm management therapy based on the first electrical signal.

18. The method of claim 17, further including:

transmitting ultrasound from the first ultrasonic element; and

receiving ultrasound at the first ultrasonic element.

19. The method of claim 18, in which the second ultrasonic element is located in an electronics unit.

20. The method of claim 18, in which the second ultrasonic element is located in a second heart chamber that is different from the first heart chamber.

21. The method of claim 17, further including:

transmitting ultrasound from the second ultrasonic element; and

receiving ultrasound at the first ultrasonic element.

22. The method of claim 21, in which the second uLtrasonic element is located in an electronics unit.

23. The method of claim 21, in which the second ultrasonic element is located in a second heart chamber that is different from the first heart chamber.

24. The method of claim 17, further including:

transmitting ultrasound from the first ultrasonic element; and

receiving ultrasound at the first ultrasonic element.

25. The method of claim 17, further including providing an autocapture function based on the first electrical signal.

26. The method of claim 17, further including detecting a volume of a mechanical heart contraction based on the first electrical signal.

27. The method of claim 17, further including detecting a second electrical signal including intrinsic electrical heart activity information.

28. The method of claim 27, further including detecting occurrences of heart activity based on both the first and second electrical signals.

29. The method of claim 27, further including detecting a dissociation between (1) an occurrence of heart activity based on the first electrical signal and (2) an occurrence of heart activity based on the second electrical signal.

30. The method of claim 27, further including recognizing an arrhythmia based at least in part on the first electrical signal.

31. The method of claim 17, further including controlling delivery of the ultrasound energy for disrupting cell membranes.

32. The method of claim 17, further including controlling delivery of the ultrasound energy for releasing a steroid.

33. The method of claim 17, further including obtaining blood flow information from the first electrical signal.

34. The method of claim 17, further including communicating infonration based on the ultrasound from an electronics unit to a remote programmer.